Melatonin is a hormone produced by the pineal gland from the body’s supply of serotonin. Its best known use is to help regular the daily sleep/wake cycle. It also functions as a strong antioxidant and an immune system booster. It’s even been studied and advocated for use in preventing damage to humans from ionizing radiation. For such reasons, many in the anti-aging community advocate taking supplemental melatonin before each night’s sleep to improve overall health and sleep quality.
In healthy people, the dark hours of the day when you should be sleeping result in increased release of melatonin. It helps you fall asleep and stay asleep until the morning. Exposure to light, particularly bright lights, diminishes the body’s production of melatonin and at least partly explains why many people do not sleep well during the day even if they are very tired.
To have good melatonin levels and healthy sleep, you should keep your room dark. Even soft lighting can significantly lower the body’s melatonin production:
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Quoted from Wikipedia’s Melatonin article
Melatonin levels at night are reduced to 50% by exposure to a low-level incandescent bulb for only 39 minutes, and it has been suspected that women with the brightest bedrooms have an increased risk for breast cancer. Reduced melatonin production has been proposed as a likely factor in the significantly higher cancer rates in night workers.
Some people who have trouble sleeping find that melatonin is very beneficial for making them feel drowsy enough to fall asleep. It’s earned a reputation for being very helpful for people who travel between time zones as it can help them more rapidly reset their wake/sleep cycles to match the local time.
Melatonin Benefits in Cancer Patients
The connection between low melatonin and cancer has been known for decades. In some countries they have acknowledged that night shift workers and people exposed to nighttime bright lights on a frequent basis are essentially being exposed to a carcinogenic environment:
The detrimental effects of light at night were first explored by epidemiological studies investigating cancer risk in shift workers. It began in the late 1970s, when it was proposed that the pineal gland (which produces the hormone melatonin, a modulator of sleep/wake patterns) influenced the development of breast cancer . However, it was not until the late 1980s, when Richard Stevens postulated that night-time light exposure may represent a risk factor for breast cancer development in Westernized societies, that research in this area began in earnest . Fast-forward to today, and there is now strong epidemiological and experimental work in support of the hypothesis that light at night impacts breast cancer risk and development, which will be discussed below. Indeed, the International Agency on Research on Cancer has classified shift work as “probably carcinogenic to humans” and some countries (e.g., Denmark) have classed breast cancer as an occupational health risk associated with shift work. More recent studies have also begun to look at the association between exposure to light at night in general (outside the context of shift work) and risk for developing certain types of cancer such as breast and prostate cancer.
Light exposure during the night may increase breast cancer risk via several mechanisms. First, light at night affects certain cancers by decreasing levels of the pineal hormone melatonin, which is suppressed when an individual is exposed to light at night. Melatonin is produced and released primarily during the night, with a longer night corresponding to an increased duration of melatonin production, and is important for coordinating endogenous circadian timing. Melatonin production is disrupted by light at night, with bright light intensities suppressing melatonin secretion for the entire night. Melatonin may influence breast cancer development via two primary routes: (a) a decrease in melatonin may increase estrogen/progesterone signaling, two known breast cancer promoters; and/or (b) melatonin may act directly on cancer and cancer-fighting cells that have melatonin receptors, reducing tumor growth. Melatonin can also affect tumor onset and development via its actions on oxidative stressors .
Many studies have been done on boosting melatonin levels in cancer patients to look for beneficial effects. Melatonin boosts the immune system, helping it to overcome immunosuppression from chemotherapy and keep cancer patients healthier. It reduces the damage and side effects from chemotherapy, probably due to its antioxidant properties. Such improvements include reduced nausea and vomiting, less depressed blood platelet cell counts (thrombocytopenia), and improved one year cancer survival rates for several types of metastatic cancers. For more detailed information on using melatonin in cancer patients, please see Life Extension’s article on cancer chemotherapy.
Sleep Difficulties May Relate to Inadequate Tryptophan, Serotonin, and Melatonin
The body uses a portion of its available tryptophan (one of the eight essential amino acids used to build proteins) to product 5HTP and serotonin. Serotonin deficiencies are often cited as a source for symptoms of depression. Whole classes of medications such as SSRI antidepressants have been developed to modify the body’s usage of serotonin to treat such symptoms.
Since sleep difficulties are among the primary symptoms of depression, it’s quite possible that many depressed individuals could be suffering from both low serotonin and melatonin at the same time. Unfortunately, it is common for doctors to whip out the prescription pad for an antidepressant before even considering that serotonin is just one factor and that improved diet and nutritional supplementation may be more helpful than medication.
One way to help boost your levels of melatonin may be to eat a more healthy diet with plenty of protein-rich foods high in the amino acid tryptophan and to add in tryptophan supplements after dinner or at bedtime.
Because of the way the body converts tryptophan to 5HTP to serotonin to melatonin, it’s quite possible that a dietary deficiency of tryptophan or other nutrients (such as vitamin B6, magnesium, and vitamin D) that impact this conversion chain could result in low levels of melatonin that impair sleep and along the way, via inadequate levels of serotonin, lead to depression.
If you avoid most dairy products, fish, poulty, and beef, then you’re more likely to have a deficiency of tryptophan as those are all good sources for it. Even if you have enough tryptophan, deficiencies of vitamin B6, magnesium, and vitamin D can impair production of adequate serotonin and melatonin.
Some theorize that the epidemic of low vitamin D levels, though to be in part caused by little time spent outdoors in the sunlight, may be related to increasing rates of sleep disorders. It is very easy to get extra vitamin D inexpensively via supplementation even if you don’t have time to spend outdoors, but it’s unclear if that is enough on its own. Daytime bright light may affect multiple biological functions beyond vitamin D and melatonin levels, so it may be beneficial to try to get some morning bright light after waking up for the day even if you are taking vitamin D and melatonin supplements.
Because of the many variables affecting melatonin production, even an improved diet might still leave you with too little melatonin for an extended period of time. So if you’re having significant trouble sleeping many nights then it is probably worth giving melatonin a try to see if it can help you.
Melatonin Dosage Safety
Melatonin is available in a wide range of dosages from about 300 mcg (micrograms) to 10 mg (milligrams) per tablet or capsule. Some versions include time-release melatonin, but most are immediate release. This has prompted many to wonder about the appropriate dosage and particularly the safety in the larger dosages.
Some studies point out that even the 300 mcg dosages are often enough to raise blood serum melatonin to typical sleep time levels. However, the perceived sleep-inducing effect varies considerably. Anecdotally, it appears that younger people experience less sleep-inducing effect from small dosages of melatonin than older people do. This may be related to how melatonin production declines with age. A 300 mcg melatonin dose might make a 70 year old fall asleep quickly but have little affect on a 20 year old.
For starters, I would recommend trying products with between 1 mg and 3mg for people under around age 60 and between 300 mcg and 1 mg for those who are older. Advice from your similar-aged siblings may be helpful if they have tried melatonin themselves.
As far as safety concerns go, the biggest is that melatonin can cause enough fatigue or grogginess to impair the ability to safely perform attention-demanding activities such as driving a car. I’d highly recommend that you not take melatonin within a few hours of any time you have to be doing anything that might be dangerous if you were to doze off even for a moment.
It takes about half an hour for melatonin to have a strong effect on many people. So the best time to take melatonin may be about 30 to 60 minutes before when you intend to get several hours of sleep at night.
It probably is best for most people taking melatonin for sleep purposes to not to use it during the daylight hours. This is because it may confuse the body since the melatonin levels will be indicating its time for sleep but other signals, particularly anything that is triggered by daytime light, will be saying it is time to be awake.
However, there are studies of dosing protocols that contradicted this thinking and tested dosages throughout the day, including daylight hours, to support an immune system boosting effect. I’d recommend increased caution about this usage pattern until after you at least understand how melatonin affects you personally when you use it at bedtime.
The body generally does a fairly complete job working off immediate-release melatonin after a few hours. The half-life for melatonin in a healthy person is generally reported as being around 20 minutes to 60 minutes, but some studies say as much as two hours. Figure that most of the effect of any melatonin you take will be gone within an hour to a few hours depending upon your metabolism. This is part of why time-release melatonin supplements may be more helpful than immediate-release supplements if you have problems waking up in the middle of the night.
Products that combine an immediate-release dose of melatonin plus a time-release dose may be better for people who have trouble falling asleep and staying asleep. The Swanson Health Products dual release melatonin tablets to the left include 1.5 mg immediate release and 1.5 mg additional released over the next 6 to 8 hours. I don’t recommend release lengths any longer than this as you’re more likely to be groggy at your desired waking time.
When you first try melatonin, I’d suggest you do so on a night before a day on which you don’t have to be up and out the door early. If you haven’t noticed any effect by an hour or two after you take it, the dosage probably isn’t adequate for you. If you wake up after eight or so hours of sleep and feel more groggy than usual, then the dosage may have been too much.
If you wake up groggy from melatonin, the grogginess probably shouldn’t last more than an hour or so after waking unless there is some other factor at work. For instance, if you used a large dosage of a long-lasting time-release melatonin product, that could lead to long-term grogginess. Alcohol, anxiolytic medications including benzodiazepines such as Xanax (alprazolam) and Valium (diazepam, also sold as Antenex) and other sedatives, and certain sleep and depression drugs such as Ambien, Lunesta, and Trazodone that are commonly used by people with poor sleep would likely make any melatonin-related grogginess more intense or be a cause of such a condition on their own even without taking any melatonin.
Most people needn’t worry much about melatonin supplements being dangerous beyond the effects of simple grogginess. The toxicity studies noted at the end of this article make it reasonably clear that even months of taking 100 mg or more melatonin per day does not appear to cause significant adverse affects for most people.
But there a few people who may be advised to avoid melatonin. People who have immune system problems such as autoimmune disorders such as lupus or rheumatoid arthritis or certain cancers such as leukemia or other cancers affecting immune cells or involving hormones related to melatonin could be harmed by it. For instance, there are some concerns that melatonin may raise prolactin production and this could be harmful for men with prostate cancer. The reason for such concerns is often tied to how melatonin boosts immune system function. If you have an autoimmune condition or a cancer involving your immune system cells, that is probably not a helpful effect as you don’t want your already overactive immune system ramping up attacks on healthy parts of your body.
Scientists have attempted to determine the levels of melatonin that would cause a toxic reaction in rats. In a 1999 study entitled Maternal and developmental toxicity evaluation of melatonin administered orally to pregnant Sprague-Dawley rats, they report not finding any level at which adverse effects were evident in female rats gestating rat fetuses. At dosages of above 200 mg/kg/day (roughly equivalent to a few grams per day for even a human child), there was some evidence of developmental impact to the gestating rats and side effects such as reduced body weight and food intake. Below 50 mg/kg/day, no side effects were noticed.
In a trial of 700 mg per day of melatonin in malignant melanoma (a form of skin cancer) patients, patients took 4 doses per day for 33 weeks. Toxicity and side effects were reported as minimal with fatigue being the main complaint in 17 out of 40 patients.
Another trial involved testing melatonin as a contraceptive at 300 mg per day for four months in 12 human female subjects. There appeared to be no adverse side effects in this small trial.
In yet another trial, they tried 1000 mg per day in four doses (250 mg per dose) for about a month in five patients with hyperactive skin pigmentation. Extensive blood testing and health monitoring found no evidence of toxicity or side effects.
Given that 3 mg melatonin tablets are probably the most common dosage, you should be reassured that you’re not likely to hurt yourself with commonly available doses of melatonin even if you take a few of them per day to help with your sleep. Just be sure to allow enough time to wake up fully before doing anything attention-demanding and safety-critical such as driving a car.
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